Waterjet cutting cuts material with a very high-pressure water jet, at several thousand bar, to which a mineral abrasive (garnet) is added for hard materials. Without abrasive, pure water cuts soft materials: gaskets, rubber, foam, insulation, foodstuffs. Because the process is “cold”, it creates no heat-affected zone, no heat distortion and no hardening of the edge.
A high-pressure pump feeds a cutting head whose sapphire or diamond nozzle focuses the jet; the abrasive is mixed with the water in a carbide tube. The CNC machine moves the head above a water tank that supports the sheet. Some tilting heads compensate for the taper of the cut. Practically anything can be cut: steel, stainless steel, aluminium, titanium, copper, stone, glass, ceramic, composites. Thickness can exceed one hundred millimetres, but quality falls as it increases, the cut becoming tapered and striated. Accuracy is in the order of a tenth of a millimetre on common thicknesses, and a slower cut gives a smoother, straighter edge.
Waterjet is the choice for heat-sensitive materials, composites and non-metallic materials, thick sections where the edge must not be altered and parts that are machined afterwards: a blank is cut from a thick plate before machining. It is slower and costlier per metre than laser cutting on thin sheet, because of the consumables (abrasive, nozzles). See also the guide laser, plasma or waterjet, and plasma cutting for thick metals. To have plates cut, see the sheet metal and cutting page.
In a quote request. Supply a DXF or a 3D model, the material and the thickness. State the edge quality you want, as it governs the speed and therefore the price, and which face of the part must have the best quality: the jet entry side is better defined than the exit side. Say whether the part is machined afterwards, which allows a machining allowance to be left.